1. Field of the Invention
The present invention relates to a sheet feeding apparatus and an image forming apparatus. More particularly, the invention relates to a configuration positioning of a restricting member which is movably arranged at a sheet cassette to restrict a sheet position.
2. Description of the Related Art
Recently, a configuration in which a sheet is fed to an image forming portion for forming an image has been widely employed for an image forming apparatus such as a printer and a copying machine. It is common that such an image forming apparatus has a sheet feeding apparatus which automatically feeds a sheet accommodated in a sheet cassette to an image forming portion by a sheet feeding member while the sheet cassette is mounted to be detachably attachable to a body of the image forming apparatus.
A universal cassette capable of accommodating sheets of a variety of sizes within the same cassette is employed as the sheet cassette for such an image forming apparatus. Here, at a sheet accommodating portion of the universal cassette, a rear end restricting member which restricts the position of the rear end of the sheet accommodated in the sheet accommodating portion in the sheet feeding direction is disposed in order to accommodate sheets of different sizes. In addition, a side end restricting member which restricts the position in the direction perpendicular to the sheet feeding direction (hereinafter, called the width direction) is disposed.
With the universal cassette, the rear end of the sheet is restricted by the rear end restricting member while the side end is restricted by the side end restricting member. Thus, the top end of the sheet is always set at a predetermined position. In this manner, stable feeding of the sheet is performed regardless of the sheet size.
By the way, when the universal cassette is detached from and attached to the image forming apparatus body, for example, there is a case that these restricting members are moved by inertial force or impact of the sheet generated by the detaching and attaching operation. Then, when the restricting member is moved as mentioned above, the sheet may not be restricted at the appropriate restricting position. Consequently, it may cause problems such as poor feeding, skew feeding and double feeding during the sheet feeding operation.
In order to prevent the movement of the restricting member by the inertial force or the impact, a fixing mechanism to fix the restricting member is disposed to a conventional universal cassette. The mechanism disclosed in Japanese Patent Application Laid-open No. 2007-197159 is the fixing mechanism which firmly fixes the restricting member.
In this mechanism, two rows of rack teeth which are configured with a plurality of triangular teeth are arranged stepwise at the bottom surface of the cassette. Then, two rows of teeth which are configured with a plurality of triangular teeth to be engaged respectively with the stepwise arranged rack tooth rows are disposed at the restricting member which is movable frontward and backward. Further, the frontward movement of the restricting member is restricted by one tooth row of the restricting member being engaged with one rack tooth row of the cassette. The backward movement of the restricting member is restricted by the other tooth row of the restricting member being engaged with the other rack tooth row of the cassette. Accordingly, the restricting member is firmly fixed due to the engagement of both the tooth rows of the restricting member with both the rack tooth rows of the cassette.
The two tooth rows which are disposed at the restricting member are arranged at a holding portion which is supported being free to turn. By turning the holding portion, the two tooth rows of the restricting member are simultaneously released from the two rack tooth rows.
In the case that the two rack tooth rows and the two tooth rows are respectively arranged stepwise, the height of the cassette body becomes high due to the height necessary for accommodating the above-mentioned configuration. As a result, the universal cassette is upsized and the cost thereof is increased. Further, the image forming apparatus to which the cassette is mounted is upsized.
The present invention has been made in view of these circumstances, and an object thereof is to provide a sheet feeding apparatus and an image forming apparatus which can reliably hold a restricting member at a restricting position without upsizing a sheet cassette.